Memory devices reside in many computers and electronic products to store data.
A typical memory device has many memory cells and some redundant (spare) cells. When some of the memory cells are defective, the defective memory cells can be replaced with redundant cells to repair the memory device. This repairing method saves the entire memory device when only a few memory cells are defective.
Certain defects are repairable. Some defects are irreparable, causing the entire memory device to be discarded.